Oliver Ringelstein studied mechanical engineering (Dipl.Ing.) at RWTH Aachen University. In 1993, he founded INTEWA GmbH and has since been dedicated to the development and dissemination of technologies for sustainable water management. The focus is on water reuse and rainwater management. He is a member of various professional associations and networks, including DGNB, fbr, ARCSA, BuGG, GWP (German Water Partnership), IRHA, digitalHUB and kanthari. He is also alliance coordinator at AIX-Net-WWR, an Aachen-based research and development network for wastewater reuse. INTEWA now supplies its technologies to over 20 countries worldwide. At its location in Aachen, the company itself is water self-sufficient and energy neutral.